A powerful typhoon, named Dolphin, has brought disruption to Japan's Okinawa island and is set to make landfall on China's eastern coast. The storm, reaching maximum wind speeds of 162km/h (101mph), has cut power to over 44,000 buildings and left at least five people injured in Okinawa. Flights in and out of Naha International Airport were cancelled ahead of the storm's arrival. The typhoon is expected to hit China late on Sunday or early Monday, prompting authorities there to shut down ports and schools. In Zhejiang province, a coastal alert has been raised to its highest level, leading to the halt of port and ferry services. The main Japanese islands affected are Okinawa and Amami in the southwest, with five elderly people sustaining non-life-threatening injuries due to strong winds. This year's typhoon season in the western Pacific, which usually spans from May to October, is expected to be more intense due to a strong El Niño. In an average year, around three cyclones reaching tropical storm strength make landfall in Japan, with some classified as typhoons like Dolphin. While hurricanes form in the Atlantic or eastern Pacific, typhoons originate in the north-west Pacific.